Don, changing the measuring bar is simply a matter of pulling out the pin holding the spacer bar, pulling back the slide mechanism and inserting the new bar, making sure the square washer is in the channel. You can even speed things up by scribing a fine line on the top of the measure bar so you can eyeball the correct charge and refine once you're ready to go.

Changing the priming system is two hex-head bolts (which, conveniently use the same wrench as the powder measure) and unhooking a spring. Then you change the tube by unscrewing the top of the priming assy, pulling out one tube and dropping in the other.